1. Field of the Invention
The present invention relates to a thin-film piezoelectric element having a piezoelectric thin film and a method of making same.
2. Related Background of the Invention
A thin-film piezoelectric element in the field of this technology is disclosed, for example, in Japanese Patent Laid-Open No. 2003-229611. To manufacture the thin-film piezoelectric element disclosed in the patent publication, firstly two sheets of silicon substrates are prepared, and a film of MgO preferentially oriented on a (200 ) plane is formed on the surface of each substrate. Secondly, a first electrode film, a piezoelectric film, and a second electrode film are laminated in this order on each of the substrate having the formed MgO film thereon to prepare two sheets of laminate substrates. Thirdly, these two laminate substrates are stuck together using an adhesive in a position in which the respective electrode films face with each other. Fourthly, only one silicon substrate is removed by etching, followed by forming an electrode pattern on the surface exposed by the removal of the silicon substrate. After that, the other silicon substrate is removed by etching, thus to complete the making of the thin-film piezoelectric element. Even after removing the silicon substrate by etching, however, the MgO film is left on the top and bottom surfaces of the thin-film piezoelectric element.
The above-described conventional thin-film piezoelectric element has, however, problems. That is, as described in the patent publication, the MgO film degrades the characteristics of the element because the MgO thin film left on the thin-film piezoelectric element decreases the displacement magnitude of the piezoelectric film. Although the patent publication describes the improvement in the displacement magnitude of a piezoelectric film by removing the MgO film, the treatment needs additional work and time, which increases the manufacturing time and cost.
The present invention was completed to solve the above problems, and an object of the present invention is to provide a thin-film piezoelectric element which reduces the influence of the oxide film left on the electrode film on the degradation of the element characteristics, and to provide a method of making same.